From inflation to a zero cosmological constant phase without fine-tuning

We show that it is possible to obtain inflation and also solve the cosmological constant problem. The theory is invariant under changes of the Lagrangian density $L$ to $L+\mathrm{const}.$ Then the constant part of a scalar field potential $V$ cannot be responsible for inflation. However, we show that inflation can be driven by a condensate of a four index field strength. A constraint appears which correlates this condensate to $V.$ After a conformal transformation, the equations are the standard GR equations with an effective scalar field potential ${V}_{\mathrm{eff}}$ which has generally an absolute minimum ${V}_{\mathrm{eff}}=0$ independently of $V$ and without fine tuning. We also show that, after inflation, the usual reheating phase scenario (from oscillations around the absolute minimum) is possible.